1// SPDX-License-Identifier: GPL-2.0
2/*
3 *  This code maintains a list of active profiling data structures.
4 *
5 *    Copyright IBM Corp. 2009
6 *    Author(s): Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
7 *
8 *    Uses gcc-internal data definitions.
9 *    Based on the gcov-kernel patch by:
10 *		 Hubertus Franke <frankeh@us.ibm.com>
11 *		 Nigel Hinds <nhinds@us.ibm.com>
12 *		 Rajan Ravindran <rajancr@us.ibm.com>
13 *		 Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
14 *		 Paul Larson
15 */
16
17#define pr_fmt(fmt)	"gcov: " fmt
18
19#include <linux/init.h>
20#include <linux/module.h>
21#include <linux/mutex.h>
22#include <linux/sched.h>
23#include "gcov.h"
24
25int gcov_events_enabled;
26DEFINE_MUTEX(gcov_lock);
27
28/**
29 * gcov_enable_events - enable event reporting through gcov_event()
30 *
31 * Turn on reporting of profiling data load/unload-events through the
32 * gcov_event() callback. Also replay all previous events once. This function
33 * is needed because some events are potentially generated too early for the
34 * callback implementation to handle them initially.
35 */
36void gcov_enable_events(void)
37{
38	struct gcov_info *info = NULL;
39
40	mutex_lock(&gcov_lock);
41	gcov_events_enabled = 1;
42
43	/* Perform event callback for previously registered entries. */
44	while ((info = gcov_info_next(info))) {
45		gcov_event(GCOV_ADD, info);
46		cond_resched();
47	}
48
49	mutex_unlock(&gcov_lock);
50}
51
52/**
53 * store_gcov_u32 - store 32 bit number in gcov format to buffer
54 * @buffer: target buffer or NULL
55 * @off: offset into the buffer
56 * @v: value to be stored
57 *
58 * Number format defined by gcc: numbers are recorded in the 32 bit
59 * unsigned binary form of the endianness of the machine generating the
60 * file. Returns the number of bytes stored. If @buffer is %NULL, doesn't
61 * store anything.
62 */
63size_t store_gcov_u32(void *buffer, size_t off, u32 v)
64{
65	u32 *data;
66
67	if (buffer) {
68		data = buffer + off;
69		*data = v;
70	}
71
72	return sizeof(*data);
73}
74
75/**
76 * store_gcov_u64 - store 64 bit number in gcov format to buffer
77 * @buffer: target buffer or NULL
78 * @off: offset into the buffer
79 * @v: value to be stored
80 *
81 * Number format defined by gcc: numbers are recorded in the 32 bit
82 * unsigned binary form of the endianness of the machine generating the
83 * file. 64 bit numbers are stored as two 32 bit numbers, the low part
84 * first. Returns the number of bytes stored. If @buffer is %NULL, doesn't store
85 * anything.
86 */
87size_t store_gcov_u64(void *buffer, size_t off, u64 v)
88{
89	u32 *data;
90
91	if (buffer) {
92		data = buffer + off;
93
94		data[0] = (v & 0xffffffffUL);
95		data[1] = (v >> 32);
96	}
97
98	return sizeof(*data) * 2;
99}
100
101#ifdef CONFIG_MODULES
102/* Update list and generate events when modules are unloaded. */
103static int gcov_module_notifier(struct notifier_block *nb, unsigned long event,
104				void *data)
105{
106	struct module *mod = data;
107	struct gcov_info *info = NULL;
108	struct gcov_info *prev = NULL;
109
110	if (event != MODULE_STATE_GOING)
111		return NOTIFY_OK;
112	mutex_lock(&gcov_lock);
113
114	/* Remove entries located in module from linked list. */
115	while ((info = gcov_info_next(info))) {
116		if (gcov_info_within_module(info, mod)) {
117			gcov_info_unlink(prev, info);
118			if (gcov_events_enabled)
119				gcov_event(GCOV_REMOVE, info);
120		} else
121			prev = info;
122	}
123
124	mutex_unlock(&gcov_lock);
125
126	return NOTIFY_OK;
127}
128
129static struct notifier_block gcov_nb = {
130	.notifier_call	= gcov_module_notifier,
131};
132
133static int __init gcov_init(void)
134{
135	return register_module_notifier(&gcov_nb);
136}
137device_initcall(gcov_init);
138#endif /* CONFIG_MODULES */
139